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Discussion Starter · #1 ·
I have a misfire and general loss of power (even before the misfire kicks in).

It started this morning on the way to work, the RAC found no fault but are sending a dedicated VAG tech out to me.

On raising the bonnet, there was a smell of burning and a small amount of smoke from the rear of the engine around the turbo area. Unable to tell where it was coming from though as it's so windy.

Engine oil is clean, level is good and no metallic bits in the oil on the dipstick.

Any ideas on what it could be?

RAC chap advised don't drive home like it.
 

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Turbo gasket fried ? or possibly an oil leak from somewhere else, smoking as it hits something hot.

Keep your eye on the oil level everyday if I were you and get it in somewhere trustworthy asap. Have you got a Liquid TT I can't remember, I guess not or you would have posted up a fault code or more detail?

Charlie
 

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Discussion Starter · #3 ·
Could it be a split turbo hose?

Would that cause smoke around that area?
 

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Discussion Starter · #6 ·
Thanks guys - there is no sign of any oil leaking, nothing on the drive or the car park where I park everyday.

The engine misfires badly under accelleration and load and now generally lacks power full stop.

When we did a test run with the RAC chap in the car I pulled up in the car park and popped the bonnet and that was when I noticed a hot smell and then saw smoke drifting up, it did not look blue or smell like engine oil.

I'm wondering whether Charlie is on the right track with a turbo gasket failure.
 

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Discussion Starter · #7 ·
This car has been totally reliable for 3 years and 105k miles.

Bit of a bummer it has just happened after splashing out this week on a new set of BBS LM's and new tyres the other week and the coilovers the other week are/were being fitted this weekend too.

I've also just bought a new set of wheels and tyres and front hub bearings for my other car only yesterday.

Might not have spent so much had I known this was going to happen :?
 

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Discussion Starter · #8 ·
[smiley=bigcry.gif] [smiley=bigcry.gif] [smiley=bigcry.gif] [smiley=bigcry.gif]
 

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KentishTT said:
Thanks guys - there is no sign of any oil leaking, nothing on the drive or the car park where I park everyday.

The engine misfires badly under accelleration and load and now generally lacks power full stop.

When we did a test run with the RAC chap in the car I pulled up in the car park and popped the bonnet and that was when I noticed a hot smell and then saw smoke drifting up, it did not look blue or smell like engine oil.

I'm wondering whether Charlie is on the right track with a turbo gasket failure.
How is your TIP, is it uprated? obviously not to explain the oil but the misfire, is it def a misfire or could it be the hose collapse causing a stuttering in performance - I would not expect to see an oil leak on the drive unless it is a major leak as the undertray will probably disguise anything relatively minor.

Charlie
 

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Discussion Starter · #10 ·
No uprated TIP and my hoses are all the original ones since new as far as I know.

They have never caused any troubles, so if it aint broke....... :wink:

Could be a collapsed hose or maybe a hose at the back is split?

Funny how it started so suddenly; the RAC man thinks it may also be the coil pack on it's way out and another problem too.

RAC just called and VAG specialist is on his way :)
 

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KentishTT said:
No uprated TIP and my hoses are all the original ones since new as far as I know.

They have never caused any troubles, so if it aint broke....... :wink:

Could be a collapsed hose or maybe a hose at the back is split?

Funny how it started so suddenly; the RAC man thinks it may also be the coil pack on it's way out and another problem too.

RAC just called and VAG specialist is on his way :)
I thought he had changed a coilpack already as that was my first thought ?

Charlie
 

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Discussion Starter · #12 ·
Mine too and that was what I reported when I called them.

Just a bit worrying that there was smoke drifting up from the back after a spirited sprint down the road and back showing the RAC chap the fault.

I must say that the RAC chaps were excellent, really dug their heels in with the people they were speaking with on the phone to get this other VAG specialist chap out to thoroughly check the car over. Had 2 of them on different phones giving their controllers an ear bashing :)
 

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KentishTT said:
Mine too and that was what I reported when I called them.

Just a bit worrying that there was smoke drifting up from the back after a spirited sprint down the road and back showing the RAC chap the fault.

I must say that the RAC chaps were excellent, really dug their heels in with the people they were speaking with on the phone to get this other VAG specialist chap out to thoroughly check the car over. Had 2 of them on different phones giving their controllers an ear bashing :)
I expect if it weren't for the misfire you could have been driving the car for ages longer and never noticed it. Nice work from the RAC - I am a member also :)

Charlie
 

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Discussion Starter · #14 ·
The RAC diagnostics chap was brilliant, he scanned the car & only found my central locking fault do it wasn't a coilpack.

He checked the turbo as best he could by feeling pressure in each hose & commented that he thought it lost boost too quickly.

He jacked the car up on blocks took the undertray off & checked for oil leaks & just found a small trace of grease had come from a cv gaitor where it had prob been packed with too much grease but was all secure.

The drive home was ok if I built up the revs even to high revs but under a greater load & harder throttle it hesitated & felt like the turbo had been switched off.

Looks like it's a boost leak somewhere!

Sent from my iPhone using Tapatalk
 

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Are you sure a coil pack failing will show up in Vagcom? Dont think the APX shows a failing coilpack and hasnt the BAM ones got to completely fail to show up? Mine did the exact same thing as you're getting after my re-map, one day it was fine then next day took it out and really bad misfire, was ok if the revs were built up slowly but on flooring at 3000 revs popped and banged. I just guessed coil packs, bought a new set from Audi and a set of plugs, fitted them and all sorted.
Other thing is check the red hose at the back of the engine that goes to the turbo for splits, that would cause smoke if it was split :?
 

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When you say misfire do you mean popping and banging, a stuttering drop in power or just a sudden but continuous drop in power? Does the problem occur at wide open throttle or at light loads or at certain revs?

An oil leak/smell and boost leak could be the turbo outlet hose. They often develop an unobvious split as you can see in this thread: viewtopic.php?f=2&t=150849&p=1551151&hilit=split+hose+turbo#p1551151

Sparks are more difficult to strike at high boost pressure and will show up failing coilpacks etc. Pops and bangs could be coilpack wiring too if it's peished and keeps shorting out and sparking. Scattered timing can also be caused by the engine speed (crank position) sensor.
 

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Discussion Starter · #18 ·
Thanks guys!

It is very hesitant, like the car is when it hits the rev limiter. Under these conditions, the turbo does not appear to work or have much affect.

It will only do it when the throttle is depressed a fair bit and the engine under reasonable load.
You can go easy on the throttle and take the revs up quite high and it feels fine with normal performance.

It feels quite different to when my coilpacks have gone in the past, on those occasions, building up the revs to a certain limit caused the car to misfire. Revs make no difference now, it is engine load and throttle position that affects it.
 

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Coilpacks can fail by degrading insulation breaking down and not being able to withstand a high voltage but still being able to withstand a lower voltage. Under high boost the charge gas pressure is high and this requires a higher voltage to jump the spark plug gap. Consequently the coilpack breaks down instead, as the voltage rises in the ignition cycle and fails to produce a spark at the spark plug. At lower boost it works fine because the spark happens at a lower voltage, as it rises, before the breakdown voltage point is reached. This is independent of engine speed. It sounds like that sort of scenario although I can't be 100% sure.

Other coilpack faults can be more intermittent and due to shorts or breaks in the coils and be related to temperature etc. These can cause sparks to occur at wrong times in the combustion cycle and cause backfires through exhaust or inlet when the valves are still open. Similar things can happen with shorts in the coilpack wiring.

Eventually it fails completely and only fires on three cylinders and drives like a tractor.
 

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Discussion Starter · #20 ·
Thanks John.

I'm not fully certain that it is a coilpack fault yet so I'm going to check the hoses myself thoroughly as I get the same hot smell you described in the other post you linked to above. Previous coilpack failures have always brought on the check light as soon as it started misfiring, even if it was intermittent.

If all the hoses appear OK, I'm going to order a couple of new coilpacks and wait until the fault registers on the ECU or fails completely as I don't know which one it could be at the moment.
 
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